| 摘要 |
PURPOSE:To reduce the consumption of the assist gas by forming a flange part where the peripheral part of an opening part of a tip nozzle which is movably supported in a through hole in a nozzle body is extended to the side, and realizing the energization by a coil spring in the introducing direction of the assist gas. CONSTITUTION:When the assist gas is fed from a conduit tube 5, the tip surface of a tip nozzle 33 is subject to the upward force by the pressure of the assist gas. The tip nozzle 33 is elevated to the position where the force to be received by the whole tip nozzle 33 is balanced with the energizing force of the coil spring 35, and a clearance D is formed between the tip nozzle and a metal sheet 7. A flange part 33d is formed on the periphery of the opening part at the tip of the tip nozzle 33, and the tip nozzle 33 is surely separated from the metal sheet 7 because the force which the tip nozzle 33 receives from the assist gas is larger at the tip surface side. Thus, the clearance D can be set to an optimum value, and the assist gas can be ejected only in the necessary range. The laser beam is converged by a lens 4, and the metal sheet 7 is irradiated with the laser beam through a hole 33a in the tip nozzle 33. |
